The present invention relates to joysticks, and more particularly, to a photoelectric digitized joystick with improved durability and accuracy of the joystick coordinates as the result of the use of light gratings instead of a variable resistor as used in conventional variable resistance type joysticks.
Various video game machines have been developed, and have been commercialized. When first developed, these video game machines were operated by keyboards. More recently, video game machines are typically operated by joysticks. FIGS. 1 and 2 respectively show the circuit diagram and operational time sequence of a variable resistance type joystick according to the prior art. The variable resistor VR1 of the joystick is connected to a control circuit of the computer. When the computer gives a triggering command, electric current passes through VR1 and R1 to charge C1. When the voltage of C1 reaches Vres, TR1 is discharged, and one triggering cycle is completed. When the operating stick of the joystick is moved to change the impedance of VR1, the charging time in which C1 is charged to Vres is relatively changed. The computer calculates the coordinates of the joystick according to the period of the resulting time delay. Since the accuracy of the time delay is determined subject to VR1, R1 and C1, errors tend to occur when these elements are affected by temperature. Furthermore, the variable resistor is also affected by wear with use, and therefore its service life is relatively short.